Microfilm and microfiche are used extensively for storage and reproduction of records and, because of the space saving which results, the trend to keep matter which has to be stored for subsequent examination is increasing. The invention is not limited to micrographics.
There are various forms of microfilm and microfiche scanners on the market which simply project an image at the required increased scale onto a ground glass screen or similar surface so that the material can be viewed.
It is also known to provide projectors which allow copying of the microfilm or microfiche on a readable scale, and according to an earlier invention of ours such a copier comprises an adaption unit which can be fitted to a normal copier and which will then allow the microfiche or microfilm data to be reproduced by the copier, the usual copiers being of the electrostatic type in which the medium such as paper on which the copies are to be produced is fed through the machine, a light image being projected from the microfilm or microfiche onto a sensitized member which then has the image so produced developed on the member and if required transferred to a receiving sheet.
The accent has been on the production of monochrome copies but it is now found necessary to be able to copy colour images for which the monochrome copiers are not suitable, and it is an object of this invention to provide an improved copier which will be able to enlarge the image from a microfilm or microfiche to a readily readable size and to reproduce the image in colour.
A purpose for which such a device is usuable is for instance for medical study where the information stored must be of correct colour rendition for diagnostic purposes. It is thus an object of the present invention to provide a unit which will be able to reproduce pictures of the required size from coloured microfilm or microfiche sources.
It is already known to produce colour images by overprinting, in which case the image is projected through a filter of a selected colour and is printed in that colour, and, after drying, a second colour image is produced of a further selected colour and overprinted onto the first printed image and so on until the necessary total colour rendition results, it being customary for instance to use red, blue, and yellow overprints preferably with a black overprint to produce the dark shades where required. Such methods are generally satisfactory, but in the heretofor known devices it has been difficult to maintain correct and exact register, and also to achieve an effective colour rendition. It is therefore a further object of the present invention to provide a device in which succeeding images will be correctly registered and of correct colour.